Apparatus for the control of highway crossing signals



April 8, 1941. s MlSKELLY 2,237,390

APPARATUS FOR THE CONTROL OF HIGHWAY CROSSING SIGNALS n Filed April 7, 1939 2 sheets-sheet 1 INVENTOR.

April 8, 1941- s. MlsKELLY 2,237,390

APPARATUS FOR THE CONTROL OF HIGHWAY CROSSING SIGNALS Filed April 7, 1959 2 Sheets-Sheet 2 ways.

1,2 #www INVENTOR.

Patented Apr. 19d-l UNTED STATES PATENT GFFIC APARATUS FOR THE CONTROL OF HIGH- WAY CROSSING SIGNALS Samuel Miskelly, Downers Grove, Ill., assgnor t Western Railroad Supply Company,

Chicago,

11 Claims.

The present invention relates to railroad warning signals in general and particularly to a signaing system designed to accommodate the modern railroads high speed trains as Well as its relatively slow trains. More specically, the invention comprises a signal-operating system for railroad-highway crossings in which the crossing signals are operated a predetermined time period before the train arrives at the crossing regardless of the train speed.

The present application is in part a substitute for earlier filed application Serial No. 198,005, filed March 25, 1938.

It is an object of the present invention to provide a new and novel train actuated highwayrailroad grade crossing signal control system. It is another object of the invention to provide a cro-ssing signal operating system for railroads which causes the signals to be operated at a predetermined time interval before the train reaches the crossing. Still another object of the invention is to provide a crossing signal operating system for railroads which directly gauges the train speed and operates the signaling mechanism in accordance therewith. A further object of the invention is to provide a signal operating system for railroads in which the speed of the train thru a short track section determines the time or" signal operation. An additional object of the invention is to provide a crossing warning i" system for railroads in which a simple and reliable mechanism making use oi a minimum track circuit length causes the crossing signal to be operated at a predetermined time interval before the train reaches the crossing. These and other more specific objects will be apparent from reading the ioliowmg speciication and upon considering in oormeotion therewith the attached drawings.

Reierrine now to the drawings in which a preierred embodiment of the invention is disclosed:

Figure l is a diagrammatic illustration of the system comprising the present invention in the track-clear condition;

Figure 2 is a diagrammatic illustration of the time delay mechanisms electrical circuit only,

the train is farther from the crossing in order to with the track clear and in the condition illusl give the requiredwarning of the approach of the high speed trains, then the slower speed trains take an undue length of time to reach the crossing after signal operation and public dissatisfaction follows. In the signal-operating system constructed in accordance with the present invention regardless of train speed a predetermined and reasonable period always exists between signal operation and train arrival at the crossing.

Referring again to the drawings, and to Figure v1 -in particular, a preferred embodiment of the invention is illustrated. A railroad track l is seen to approach and to cross a highway 2. On its approach side the track l is divided into sections A-B, B-C, and C-D, each rail of each section being insulated at its end from the adjacent track. Across the rails of each section is a battery or equivalent source of potential, indicated by the reference characters 3, tl and 5 for sections A-B, B-C and C-D, respectively. Each section also has its normally energized relay, indicated in the same order by the characters G, 'l and 8 thru which current fiows, with the section clear, from the section battery. Adjacent the track l at its crossing with the highway 2 is a signal, indicated generally by the reierence character 9, which is to be operated at a predetermined time interval before the train reaches the crossing and which may be of any well known type and include flashing, lights, bells andl gate arms if desired.

To eiect this desired operation of the crossing signal there is provided a time-delay mechanism, now speoically described, which is actuated by a train passing thru the sections and operating the relays which are parts of an electrical circuit. Thetime-delay mechanism comprises an electric motor M having a field F and a shaft l2. Motor M is of a variable speed type adapted to be controlled by variations in the voltage impressed thereon.. For this purpose a variable resistance Ris connected in series therewith which includes a plurality of taps RI, R2, R3, R4, etc.

Driven by the motor shaft I2 thru gears I4, I5, I6 and I1, with an intermediate shaft I8 between gears I and I6, and pinion I9 carried by a second shaft which is actuated by final gear I1, is a toothed rack which is vertically slidable in its mounting base 26. Rigid upper and lower arms 2S and 29 extend laterally from the rack, for a purpose to be explained, and with a suspended weight 21 complete the vertically movable unit which is adapted to be lifted by the motor and to descend under the actuation of gravity turning the gears and motor as it does so.

A friction brake 32 is provided to lock the vertically movable unit in its uppermost position by exerting a locking force on the side of gear I4 under the actuating force of a solenoid 33 when the latter is energized, a tension spring 34 serving to hold the brake inoperative when the i solenoid is unenergized.

To vary the motor speed there is provided a traveling contact 36 which is mounted by an insulator 31 upon an internally screw-threaded carrier 38. externally threaded shaft 39 which is actuated by a gear 40 driven by previously mentioned gear l5. Shaft 39 extends along the resistance R and the path of contact 36 is such that it successively contacts the stationary-contacts RI, R2, R3, etc. to vary the resistance in the motor circuit.

The electrical circuits which operate the time delay mechanism and which are operated thereby are now described, particular reference being had to Figures 1 and 2 in which a track-clear condition is present.

The signal 9 at the crossing is of the normally energized type and in series therewith are the contacts IIIA and 4IB of the relay 4I which is controlled by the time-delay system. With current passing thru the relay 4I the signal 9 remains inoperative but with the relay 4I de-energized the signal is immediately operated.

First, with reference to the track relays, relay 6 of section A--B has a single movable contact 6A which is normally open and out of contact with stationary contact B. Movable contacts 1A and 'IC of relay 1 in section B-C are normally closed with stationary contacts 'IB and 1D, respectively, with relay 1 energized. In section C-D in relay 8 the contacts 8A and 8B are closed with the relay energized. The flow of current is primarily controlled by these relays as will be apparent.

A battery B is connected in series with motorl M with its variable resistance R and controlling the flow of current to the motor are the traincontrolled contacts BA, 6B, 1A, 1B; and the rackcontrolled movable and stationary contacts 42 and 43, all in series with the battery. Contacts 3A and 6B are normally open with section A-B clear and current passing thru relay 5, the other contacts being normally closed. With a train in section A-B, however, the relay 6 is shorted and contacts 6A and SB closed and during such period the motor M rotates and at an increasing speed as hereinafter explained. The rack operated movable contact 42 is positioned in the path of rack-carried arm 28 and is adapted to be contacted thereby at its insulated end and moved from the stationary contact 43 and to a second stationary contact 44 as the rack substantially reaches the upper limit of its movement.

Also connected across the .battery B and in' Carrier 38 is itself mounted upon an `of current thru the signal 9.

is the brake solenoid 33. As rack-actuated contact 42 only closes with stationary contact 44 after the rack has moved substantially its full vertical displacement, and as current from the battery B can only pass therethru while contacts 6A, 6B and 1A, 1B respectively, are together, a condition which can exist only while `a train is within section A-B, it follows that the brake 32 controlled by solenoid 33 will only be operated upon the passage thru A-B of the slowest train. The solenoid will remain energized only until the train has entered section B-C at which time relay 1 is cle-energized and contacts 1A and 1B open. Also of interest is the fact that the closing of contacts 42 and 44 by rack arm 28 follows closely upon the opening of contacts 42 and 43 by the same arm. As the latter contacts are in series with the battery B and motor M it is evident that the motor current will be cut oi slightly before contacts 42 and 44 close. The momentum of the moving parts insures the continuance of the rack travel to accomplish the latter result, however.

In another circuit including the battery B are the contacts 1C and 1D of relay 1, 8A and 8B of relay 8, and the winding of relay 4I, the contacts 4IA and 4IB of which control the ilo-w In parallel with the contacts 1C and 1D of relay 1 are normally closed contacts 46 and 41, the latter being movable and being adapted to be contacted at its insulated end by the lower arm 29 of rack 25 to be moved from contact 46 as the rack reaches the end of its downward travel. 'I'he opening of contacts 1C and 1D upon a train entering section B-C will not, therefore, serve to cut oif the current thru the relay 4I until the rack has returned to its initial and lower position.

With the system starting in its normal condition, as illustrated in Figures 1 and 2, its operation will now be described. Let it be assumed now that a train has entered section A--B and is traveling in the direction of the highway 2. Immediately the train enters section A-B relay 6 is shorted and contacts 6A and BB close and the circuit including the motor M and battery B is completed, as illustrated in Figure 3. In Figure 3 the train has been in section A-B for a period of time and the motor M has lifted the rack a distance which is determined as hereinafter explained and which is dependent upon the time period. The time period the forward end of train is in section A-B will be referred to as TAB. Contacts 46 and 41 have been closed as a result of the movement of rack-carried arm 29.

A fast train will traverse section A-B in a relatively short time for it is one of the advantages of the present invention that section A-B can be short which characteristic eliminates undesirable factors resulting from train speed variation in long Sections. As described the motor M begins to rotate the instant the train enters A-B and the upward movement of rack 25 begins simultaneously. The motor speed is not constant, however, for as TAB increases the resistance R is cut out in successive steps and the motor speed increases.` Accordingly the rack travel is not directly proportional to TAB but instead grows relatively greater as TAB increases.

Regardless of the train speed it is desired that the signal begin its operation a predetermined period before the train reaches the highway. This Warning kperiod is a constant which may be called K and can be taken, for example,

to be 20 seconds. Referringfto Figure `1 the' dotted line X-X is a variable position on the track f 4 betweenlBand D at which the trainV is positioned when ther signal begins operation. Let TBX be the time required to travel the distanceB to X for any particular train.` Obviously for a fast Atra-in X will be farther from 1D. than for a slow l train for both are to reach the crossing during the same elapsed period from position X.` It is clear` that il the signal can be put intooperation for each particular train when it-reaches its X position that the desired result will accrue. It has been calculated that for any given train BD THX: TAB'TB-IX Where the constant K is decided upon and the distances A-B and BI'--D known, it is'clear that TBX can be calculated by substituting in the formula the value of TAB. Of course TAB is the time required by the train to travel the distance A-B, etc. As the range of train speeds is known the calculation can be done by assuming values of TAB. It is of course obvious that the proper unitsmust be used; for example, K,

, TAB and Tex in seconds andvBD and AB in feet.

The formula is derived inv the following manner:

In the present device the rack 25 is raised during the time interval TAB by the motor M and falls by gravity during the time interval TBx. As is evident from the above fo-rmula TAB and Tex do not vary according to a straight line relationship andk accordingly the rate of lifting of the rack 25 must be varied. The calculated relationship and desired time TBX is automatically arrived at by the present device for each TAB, for the motor speed is so varied that over the time interval TAB which it takes the engine of a particular train to travel from A to B the rack 25 is lifted to a particular height such that its return to its initial position under the actuation of gravity will consume TBX. As stated supra signal operation begins when rack-carried arm l29 opensl .contacts l5 and 4l.

' .Fhisfdesired relationship betweenmotor speed termining the particular height to which-the rack ,must be raised in order that it will consume a particular time TBX in falling. The values of the resistance taps RI, R2, R3,' etc. will be selected so that the motor will lift the rack to that Vheight in the' corresponding TAB time. By beginning at the minimum times TAB andTBx and increasing the valuesy thereof the-positionofleach 1 'resistance tapis determined. AIf arel'ativelydarge A number of taps is found to be necessary they can beeliminated anda constantly varying tapless resistance substituted, which is arranged to give thek same result. As the rack in its return movement remains geared directly to the motor thru the gear train it has a constant load and will travel at a substantially constant speed. In brief, the motor raises the rack at a variable, progressive rate in order that the rack will lower by gravity under load during the TBK.

Let it be assumed now that the front of the train has passed point B and has entered section B-C. Referring particularly to Figure 4 in which this condition exists it is seen that relay I is now deenergized and contacts 'IA and 'IB as well as IC and 'ID are open. The first-mentioned pair have opened the circuit of .the motor and the rack, under gravitational force, has begun its return to its initial position. While contacts IC and 'ID are open current continues to flow from the battery B thru the signal controlling relay 4I for the rack-controlled contacts 45 and 4l remain closed.

Signal operation occurs after the train has entered section B C and TBX has passed which has enabled the rack to return to its initial position and its arm 29 to open contacts 46 and 4? which opened the circuit thru the controlling relay 4| whereupon contacts IIA and LliB opened and the signal began operation.

Upon the train passing from section BC the relay 'I again picks up and closes its contacts and the control mechanism is in its initial condition except the relay 8 which is a safety relay in section C-D and which only has an opportunity to operate the signal when failure has occurred and the signal has not been operated before the train reaches C. The contacts 8A and 8B are in series with the control relay 4! and should current be passing thru that element when the train reaches C their opening insures signal operation though somewhat tardy. After the train passes D the relay 8 picks up and the control relay 4I is again lenergized the signal is returned to its inopera- `side of gear I4. So long as the train remains entirely in section A-B only the brake will remain on but upon reaching B the opening of contacts 'or travel and rack travel may be obtained by de- 'IA and 'IB vof relay I causes the solenoid to be deenergized and the brake released.

I claim:

1. In a signalling system for a highway crossing on railroads, the combination with a signal at a highway crossing, of a relatively short track section spaced from the crossing, a relatively long track section between the short section and the highway, and a' signal operating device comprising: a movable element adapted to be Wound up at a variable speed and to run down at a constant speed, a Variable speed electric motor to Wind up said element at a predetermined increasing rate during the time a train moves across the short section, means to vary the speed of Vsaid motor atea progressive rate and controlled automatically thereby to cause said movable element to be displaced 'a distance such that it can return at substantially uniform rate to its initial position a predetermined time interval prior to the train reaching the crossing, and means to operate said signal upon the return of said element to its initial position.

2. In a signalling system for a highway crossing on railroads, the combination with a railroad track and a signal, of signal operating means comprising an element normally biased to l an vinitial position and movable within limits upon the application of a moving force thereto and automatically returned to its initial position upon the removal of that force at a substantially constant speed, an electric motor energized vduring the movement of a train toward said crossing and between two points on the track means to effect rotation of said motor at an increasing rate of speed in accordance with a predetermined time-speed curve, means connecting said motor 'f to said element to apply a moving force thereto, means disconnecting said motor as said train emerges from between said two points, said element returning to its initial position upon the de-energization of said motor, and means to ac- U track section fand insulated therefrom, a highl way crossing at the opposite end of said long section, a signal at the intersection of said rai road and highway, and means to operate said signal at a predetermined time interval before a train reaches said crossing regardless of the train speed, said means comprising a movable element normally biased to one position, an electric motor connected to said element and including speed varying means to progressively increase the motor speed in a predetermined manner during the traversal of said short track section by a train, means to energize said motor during the time required for a train to travel the short section, said motor functioning to move said movable element during such time 'a distance dependent directly upon the travel of said motor, means to de-energize said motor upon the entrance of a train into the long section, said element returning lto initial position during the time period the train is in the long track section at a substantially uniform rate, characterized in that said motor speed is varied in a manner such that said element lifted .to a height for each train speed that it is returned at substantially uniform rate to its initial position a predetermined time interval before the train reaches the crossing.

4. In a signalling system for a highway crossing on fa railroad, a `short track section, a long track section adjacent one end of said short track section and insulated therefrom, a highway crossing at the opposite end of said long section, a signal at the intersection of said railroad land highway, and means to operate said signal at a predetermined time kinterval before a train reaches said crossing regardless of the train speed, said means comprising a movable element normally biased to ,one position, an electric motor connected to said element and subject to speed variation with variation in the voltage impressed thereon, means controlled by said mot-or to increase progressively the voltage across said motor during its operation, means to effect the energization .of said motor during the time interval required for a train to travel the short track section, said motor functioning to move said movable element during said time interval a distance dependent directly upon the travel of said Y l motor to vary to control vthe distance traveled by said movable element in a predetermined manner.

5. In a signalling system for a highway crossing on a railroad, a short track section, a long track section adjacent one end of said track section and insulated therefrom, a highway crossing at the opposite end of said longr section,

' a signal at the intersection of said railroad and highway, and .means to operate said signal at a predetermined time interval before a train reaches said crossing regardless of the train speed, said means comprising a movable element, means to place the signal into operation comprising a movable contact operable by said movable element, means to raise said movable element against gravity during the passage of a train thru the sho-rt track sect-ion, said means comprising a train-operated relay Aand a motor controlled thereby and connected to said movable element, motor speed controlling means operated by said motor toinorease its speed .to effect increased speed of travel in said movable element with sai-d train in said short track section, means to deenergize said motor upon the train entering said long track section, said movable element being `adapted to return by gravity to its initial position to operate said movable contact with said train in said long track section, characterized in that the speed o-f said motor is socontrolled as to displace said movable element at a height such that it can fall by gravity to operate said movable contact a predetermined time period before said train reaches the end of the long track section.

6. The construction set forth in claim 4 further characterized in that means are provided upon .a train traversing said short track section ait less than a predetermined speed to de-energize said motor and to lo-ck said movable element in place upon said movable elem-ent reaching the end of its upward travel.

7. In a signalling system for a highway crossing on va railroad, the combination with a plurality of insulated track sections at one side of a highway and a signal at the highway, orf a system for operating the signal at a predetermined time interval before .the train `arrives at the crossing regardless of the train speed, said system including a vertically slidable element, an electric motor connected thereto and including a variable resistance, means to energize said motor during the movement of a train across a first track section, means to deenergize said motor upon the entrance of the train into a second track section, means operated by sai-d motor to vary the resistance with the time of energiaation to control Ithe motor speed, 4and means to operate said signal upon the return of said element to a predetermined position, characterized in that the `resistance of said mot-or is varied in a predetermined manner so as to cause said element to be lifted vertically a, ldistance such that its return to said predetermined position lat a uniform rate occurs at a predetermined time interval before the train reaches the signal for various periods of time required for a train to travel the rst section.

8. In combination, a stretch of railroad track intersected by a highway, a highway crossing signal located adjacent :the intersection, a member normally occupying one posi-tion, means for moving said member away from said one position at a progressively increasing speed during the time interval required for a train approaching said highvvay to traverse a fixed distance and including a variable speed motor directly conneoted thereto, means eiective when the train has traversed said fixed distance for restoring said member to said one position at a uniform rate, and means responsive to `the position of said member for controlling said signal.

9. In combinati-on, a stretch of railway track intersected by a highway, a highway crossing signal located adjacent :the intersection, a vertically slidable toothed rack normal-ly occupying one posit-ion, means for raising said rack at a progressively increasing rate dur-ing the time interval required for a :train approaching the highway to traverse a xed distance and including la variable speed motor geared to said rack, means eiiec- 10. In combination, a stretch `of railroad track intersected by a highway, a highway crossing signal located adjacent the intersection, a member normally occupying one position, means for moving said member `aw-ay from said one position during the time interval required for a train approaching said highway to traverse a fixed distance, means effective when the train has tra-versed said fixed distance for restoring said member to said one position, and means responsive to the position of said member for controlling said signal, characterized in that said member moves at a progressively lincreasing speed in one direction under the actuation of a variable speed rotor of an electric motor which automatically controls means for varying its own speed at a progressive rate and in that said member moves in the opposite direction at an uniform rate.

11. In combination, a stretch of railroad track intersected by a highway, a highway crossing signal locate-d adjacent the intersection, a member normally occupying one position, means :for moving said member away from said yone position at a lprogressively increasing speed during fthe time interval required for a train approaching said highway to traverse a iixed distance and ineluding a variable speed motor directly connected thereto, means eiective upon said train traveling said fixe-d distance to de-ener-gize said motor, gravity-actuated means to return said member to said one position against the braking efrect of said motor, and means responsive to the position of said member for controlling said sfignal.

SAMUEL MISKELLY. 

